High-speed photographic or cinematographic varifocal objective



SEARCH RC Sept. 13, 1966 s. KLEMT ETAL HIGH-SPEED PHOTOGRAPHIC OR CINEMATOGRAPHIC VARIFOCAL OBJECTIVE Filed Dec. 23, 1964 I Lil-5L3,

rII rl3 r15 H7 H9 GUmer Klemf Karl Macher INVENTORS.

AGENT United States Patent 3,272,073 HIGH-SPEED PHOTOGRAPHIC 0R CINEMATO- GRAPHIC VARIFOCAL OBJECTIVE Giinter Klemt and Karl Macher, both of Bad Kreuznach, Germany, assignors to Jos. Schneider & Co., Optische Werke, Bad Kreuznach, Germany, a corporation of Germany Filed Dec. 23, 1964, Ser. No. 420,727 Claims priority, application Germany, Feb. 17, 1959, Sch 25,529; Aug. 5, 1960, Sch 28,268 6 Claims. (Cl. 88-57) This application is a continuation-in-part of our copending application Ser. No. 126,306 filed July 24, 1961 and now abandoned.

The present invention relates to varifocal objectives for photographic or cinematographic cameras.

In our US. Patent No. 3,057,257, issued October 9, 1962, there has been disclosed a varifocal attachment for camera objectives designed to reduce the aberrations normally encountered in such systems, this attachment including a fixed positively refractive front component on the object side of the system, a fixed positively refractive rear component-on the image side (i.e. next to the basic objective), and two movable intermediate components of negative refractivity. In accordance with the disclosure of the copending application, varifocal ratios of about 1:4 are realizable with relative apertures of 122.8 if the focal length of the fixed rear component is equal to or less than 75% of the focal length of the fixed front component and, simultaneously, the focal length of the more rearward movable component exceeds by at least the focal length of the more forward movable component.

The general object of the present invention is to provide a further improvement over the system disclosed in our US. Patent No. 3,057,257 so as to afford greatly increased varifocal and/ or aperture ratios in comparison therewith, with minimum residual aberrations which remain substantially constant throughout the range of adjustment.

The foregoing object is realized, in accordance with a feature of this invention, by so dimensioning the positive front component of an essentially afocal attachment that the ratio of its focal length to that of the principal objective, which in the .specific numerical example given in our aforementioned patent is greater than 4.5 :1, is reduced to less than 4:1 and if, concurrently, the first, more forwardly positioned movable component is constituted by two closely juxtaposed dispersive lens members separated by an air space preferably also of dispersive configuration. The latter may, for example, be substantially piano-convex with an axial width of the order of the axial thicknesses of the dispersive lens members bounding it; thus the width of this space may have a value intermediate the thicknesses of the two dispersive lens members. The second movable component may be a simple negative lens.

It has been found that the optical system just described enables the use of varifocal ratios as high as 6:1. A further improvement, in particular wtih respect to the relative aperture, is realizable with a modification of the principal or basic objective which, as in the issued patent,

may consist of four air-spaced members but wherein the last of these members, in accordance with another feature of the instant invention, is a biconvex lens Whose radii of curvature have absolute values with a ratio less than 1:3. Relative apertures as large as 121.8 have been achieved in this manner.

Even larger relative apertures, up to about 1:1.4, can be obtained if the second lens member of the basic objective, representing the sole negative member thereof, is constructed as a doublet with a strongly collective cemented surface.

The invention will be described in greater detail with reference to the accompanying drawing in which FIGS. 1 and 2 show two varifocal systems embodying the invention.

The system shown in FIG. 1 comprises a varifocal attachment, consisting of four components I-IV, and a fixed principal objective designated component V. The fixed front component I, of positive refractivity, consists of a nearly piano-convex singlet LI (radii r1, r2 and thickness d1), and separated from it by a small air space d2, of a doublet composed of a positive lens L2 (radii r3, r4 and thickness d3) and a negative lens L3 (radii r4, r5 and thickness d4). A variable air space d5 separates front component I from the negatively refracting first intermediate component II which consists of a nearly plano-concave doublet, composed of an approximately piano-convex lens L4 (radii r6, r7 and thickness d6) and a biconcave lens L5 (radii r7, r8 and thickness d7), and a nearly piano-concave singlet L6 (radii r9, r10 and thickness d9) separated from doublet L4, L5 by a small air space d8. Another variable air space d10 exists between lens L6 and the second intermediate component III, of negative refractivity, which consists of a single lens L7 in the shape of a negative meniscus (radii r11, r12 and thickness d11). Component III is separated by a variable air space d12 from the fixed, positively refracting rear component IV which consists of a positive lens L8 (radii r13, r14 and thickness d13) cemented onto a negative lens L9 (radii r14, r16 and thickness d14). The attachment I-IV retains its afocal character in all positions of adjustment.

The principal objective V, separated by a fixed air space d15 from component IV, is composed of four airspaced lens members L10 (radii r16, r17 and thickness r116), L11 (radii r18, 1'19 and thickness (1'18), L12 (radii r19, r20 and thickness d20) and L13 (radii r22, r23 and thickness d22). These lens members, all singlets and of positive refractivity with the exception of the second member L11 of this group, are separated from one onother by air spaces d17, 0'19 and d21.

Representative numerical values for the radii r1 to r23 and the thicknesses and separations d1 to d22 of lenses L1 to L13, based upon a median focal length f= of the overall system for an intermediate position of adjustment substantially as illustrated, along with their refractive indices n and their Abbe numbers 11, are given in the following Table I for an objective of relative aperture 1:1.8, adjustable between a minimum focal length f =40 and a maximum focal length f =240 so as to have a varifocal ratio of 1:6; the values listed for the variable air spaces d5, d10 and d12, are given for the inter-mediate position shown.

Table l Thirkncsses Lens Radii an m 11 Separations n =+336 43 LL- d1 =29.50 1. 62041 60. 3

d1 =0.65 Air Space I r =+209 80 d5 =103.00 Variable Air Space To =+1875 45 in =1a5o 1.80518 25. 5

r1 =-261 36 d1 =4.75 1. 58913 61. 2 II- r =+147A9 d8 10.00 Air S oace r =-1905 46 1.6---. do =7.50 1. 62041 60. 3

d1o=35.60 Variable Air Space T11= ---57 36 111...- L7.. dl1=5.00 1.62041 60.3

d12=55.36 Variable Air Space T13: +1025 25 di3=9.75 1. 65830 57. 3 1V m=92 32 Lg d14=4.75 1. 78470 26. 1

d15=37.50 Air Space T1s= +6221 010... d1s=21.20 1. 67003 47. 2

di1= 16.90 Air Space ris= 66 02 L11.-. d15=4.80 1.80518 25. 5

T19= +8632 V.-... d=7.65 Air Space T1o= -214.4O L12- dzo= 10.75 1. 67790 55. 5

dz1=0.15 Air Space m=+71 57 L13- dzz= 12.85 1. 62041 60. 3

dmm=424.66

The air spaces d5, d10 and (112 may be varied concurrently in order to change the overall focal length of the system between a minimum value f =40 and a maximum value f =240 in accordance with the following table:

The focal lengths f; and f of the positive front component I and the basic objective V can be calculated as +337.43 and +94.90, respectively, their ratio being thus less than 4:1. The absolute value of the ratio of the radii r22 and #23 of the last, biconvex lens member L13 of the basic objective, given as +71.57 and 386.59, respectively, is less than 1:3.

The modified system of FIG. 2 includes a varifocal attachment I to IV, composed of lenses L1 to L9 (radii r1 to r, thicknesses and separations d-l6 to (123), separated from each other by an air space d15'. Components I' and II are identical with components I and II of FIG. 1. The lenses L7, L8 L9 and L10 are similar to lenses L7, L8, L9 and L10, respectively, and the last lens L14 is of the same general construction as lens L13, but the two intermediate lens members of objective V' differ considerably from the corresponding members of objective V. Thus, the negatively refracting second lens member of component V consists of a positive meniscus L11 (radii r18, r19 and thickness d18) cemented onto a b-iconvex lens L12 (radii r19, r20 and thickness r119), their common surface r19 being strongly curved toward the image side of the system and being collective in character since the lens L11 has a higher index of refraction than its mate L12. Also, the third lens member L13 of component V is biconvex in contradistinction to the meniscus-shaped lens member L12 in FIG. 1.

Representative values for the parameters of the system of FIG. 2 are listed in the following Table II for an objective of relative aperture 1:1.4 and a varifocal ratio similar to that of the system of Table I.

The focal length f of component I equals +337.43, being the same as that of component I; the focal length f of component V can be calculated as 4-95.03, the ratio of the two focal lengths thus being again less than 1:3. The ratio of the absolute values of the radii r23, r24'-of the last lens member L14 given as +69.12 and 275.16, respectively, satisfies the requirement of being less than 1:3.

Table II Thicknesses Lens Radii and m r Separations n =+336.43 L1' d1 =29.50 1. 62041 60. 3

411' =0.65 Air S aace I r3 =+209.80

L2'-... da' =27.5O 1. 56873 63. 1

d =103.00 Variable Air Space To =-|-l875.45 L4'. div =13.50 1. 80518 25. 5

71' =-261.36 L5 111' =4.75 1. 58918 61. 2 II-- r =+147.49

d3 =10.00 Air Space rw =--1905.46 L6' di =7.50 1. 62041 60.3 Tm'= +8522 dw' =35.60 Variable A ir Space T1['= 63.17 111... L7'... 1111' =5.00 1.62041 60.3

m'= 142.58 dii =53.26 Variable Air Space r '=+980.99 L8'--- dia =13.75 1. 65830 57. 3 IV'.-. m'=92.32

L9 div =4.75 1.78470 26.1

dis =37.50 Air S 32106 m'=+64.22 L10 difl' =19.45 1.61720 54.0

dn' =19.10 Air Space T s'= fi3.42 L11.-. d s =13.85 1. 7200 50. 3

1'19'= --35. 58 L12..- d g =4.60 1. 64831 33. 8 V'. Tgu'=+58.11

dia =9.85 Air Space Tz1'=+l.53.64 L13-.. dzi' =11.70 1. 62041 60. 3

1121' =0.55 Air Space r2a'=+69.12 L14... 1123' =18.50 1. 62041 60. 3

Tzy= -275.16

dmmi'=449.86

Again, the overall focal length may be varied between the aforementioned limiting values in accordance with the following table:

Table IIA Variable Air Spaces Overall Focal Length What is claimed is:

1. An optical objective system comprising a principal objective and an afocal attachment in front of said principal objective; said attachment consisting of four components separated from one another by variable air spaces, said components including a fixed front component of positive refractivity, a first intermediate component of negative refractivity, a second intermediate component of negative refractivity and a fixed rear component of positive refractivity, said first and second intermediate components being movable, relatively to each other and to said front and rear components, into a first position in which the system has a relatively small focal length and a second position in which the system has a relatively large focal length; said rear component having a focal length equal to at most 75% of the focal length of said front component; said front component having a focal length less than four times the focal length of said principal objective; said first intermediate component consisting of two closely juxtaposed lens members of negative refractivity separated by an air space of negative configuration, said lens members being of substantially planoconcave shape with concave rear surfaces and including a singlet preceded by a doublet with a forwardly concave collective cemented surface, said singlet and said doublet each having a concave rear surface, the rear surface of said singlet being more strongly curved than that of said doublet; said principal objective consisting of four airspaced lens members including a positive first member, a negative second member, a positive third member and a positive fourth member, said fourth member being a biconvex lens with front and rear surfaces respectively having a shorter and a longer radius of curvature with an absolute ratio less than 1:3.

2. A system as defined in claim 1 wherein the radii r1 to r23 and the thicknesses and separations d1 to d22 of the lenses L1 to L13 forming part of said front component I, said first intermediate component'II, said second intermediate component III, said rear component IV and said basic objective V, based upon an overall focal length for said system whose median numerical value is 100, the indices of refraction r of all of said lenses and their Abb numbers 1 have numerical values substantially as given in the following table, the separations d5, d10 and d12 each having a first value corresponding to said first position and a second value corresponding to said second position:

Thicknesscs Lens Radii and n 1 Separations n= +336.43 LL..- (11 29.50 1.62041 60.3

di=0.65 Air Space I r3=+209.80

ri=+8327.00 L3 di=6.00 1. 80518 25. 5

= Air Space at=1a50 1.80518 25. s r1= -261.36 5 d1=4.75 1. 58913 61. 2 II Ta=+147.49

di=10.00 Air S )ace n= -1905.46 L6.... da=7.50 1. 62041 60.3 t T1n= +8522 X 35.60 dw= Air Space 2 13.40 ri1= 57.36 III L7. di1=5.00 1.62041 60.3

1 55.36 dn= Air S aace I 34.85 m= +1025.25 d13=9.75 1.65830 57. 3 IV f 4= 92.32

dii=37.50 Air Space m=+62.21 L10-.. dis=21.20 1. 67003 47. 2

dn=16.90 Air S aace ris= -66.02 L11 dia=4.80 1. 80518 25. 5

T1p=+86.32 V diq=7.65 Air Space Tzu= -214.40 L12 d2o= 10.75 1. 67790 55. 5

rzi= 62.67

dz =O.15 Air Space Tzg= +71.57 L13 d2z=12.85 1. 62041 60. 3

I First position.

1 Second position.

3. A system as defined in claim 2 wherein said intermediate components are also movable into a third position of minimum focal length and a fourth position of maximum focal length, the separations d5, d10 and d12 having substantially the values 0.41, 137.45 and 50.10, respectively, in said third position and the values 161.08, 18.58 and 14.30, respectively, in said fourth position.

4. A system as defined in claim 1 wherein said second member is a doublet with a strongly collective cemented surface curved toward the image side of the system.

5. A system as defined in claim 4 wherein the radii r1 to r24 and the thicknesses and separations d1 to d23' of the lenses L1 to L14 forming part of said front component I, said first intermediate component 11', said second intermediate component III, said rear component ,IV and said basic objective V, based upon an overall focal length for said system whose median numerical value is 100, the indices of refraction n of all of said lenses and their Abb numbers v have numerical values substantially as given in the following table, the separations d5, d10' and d12 each having a first value corresponding said second position:

6. A system as defined in claim wherein said intermediate components are also movable into a third position of minimum focal length and a fourth position of maximum focal length, the separations d5, (110 and 1112 having substantially the values 6.41, 137.45 and 48.00, respectively, in said third position and the values 161.08, 18.58 and 12.20, respectively, in said fourth References Cited by the Examiner UNITED STATES PATENTS 8/1958 Angenieux 88-57 9/1961 Turula et al. 88-57 4/1962 Yamaji 88-57 JEWELL H. PEDERSEN, Primary Examiner.

Thicknesses Lens Radil and m w 5 Separations dp 29.50 1. 62041 60.3 P05111011- ra' =l572.38

dz =O.65 Air S Jace 1'.--.- w =+209.s0 10 103.00 d Air S oace 145.71 ra' =+1875.45

do 13.50 1. 80518 25. 5 r1 261.36

d1 =4.75 1. 58918 61. 2 II.. r =+147.49

ds' =10.00 Air S aace rw =1905.46 L6... dw =7.50 1. 62041 60 3 1 35.60 dio'= Air Space 1 13.40 T11'= 63.17 III--. L7 dw=5.00 1. 62041 60.3

53.26 d1r= Air S aace 7 32.75 r1 '=+980.99 L8.--. d1a'=13.75 1. 65830 57. 3 IV' T14'=-92.32

d1s'=37.50 Air B 78.00 T10'= +6412 L10... d1o'=19.45 1. 61720 54. 00

dn'=19.10 Air Space T15 -68.42 L11--. d13'=13.85 1. 7200 50. 3

T1n'= -35.58 L12.-. dw=4.60 1. 64831 33. 8 V'--- Tao'=+58.11

dw=9.85 Air S aace m +153.64 L13.-- d2i'=11.70 1. 62041 60. 3

d22'=0.55 .Air s )ace 4 m'=+69.12 L14.-- du'=18.50 1. 62041 60. 3

1 First position.

2 Second position.

R. J. STERN, Assistant Examiner. 

1. AN OPTICAL OBJECTIVE SYSTEM COMPRISING A PRINCIPAL OBJECTIVE AND AN AFOCAL ATTACHMENT IN FRONT OF SAID PRINCIPAL OBJECTIVE; SAID ATTACHMENT CONSISTING OF FOUR COMPONENTS SEPARATED FROM ONE ANOTHER BY VARIABLE AIR SPACES, SAID COMPONENTS INCLUDING A FIXED FRONT COMPONENT OF POSITIVE REFRACTIVITY, A FIRST INTERMEDIATE COMPONENT OF NEGATIVE REFRACTIVITY, A SECOND INTERMEDIATE COMPONENT OF NEGATIVE REFRACTIVITY AND A FIXED REAR COMPONENT OF POSITIVE REFRACTIVITY, SAID FIRST AND SECOND INTERMEDIATE COMPONENTS BEING MOVABLE, RELATIVELY TO EACH OTHER AND TO SAID FRONT AND REAR COMPONENTS, INTO A FIRST POSITION IN WHICH THE SYSTEM HAS A RELATIVELY SMALL FOCAL LENGTH AND A SECOND POSITION IN WHICH THE SYSTEM HAS A RELATIVELY LARGE FOCAL LENGTH; SAID REAR COMPONENT HAVING A FOCAL LENGTH EQUAL TO AT MOST 75% OF THE FOCAL LENGTH OF SAID FRONT COMPONENT; SAID FRONT COMPONENT HAVING A FOCAL LENGTH LESS THAN FOUR TIMES THE FOCAL LENGTH OF SAID PRINCIPAL OBJECTIVE; SAID FIRST INTERMEDIATE COMPONENT CONSISTING OF TWO CLOSELY JUXTAPOSED LENS MEMBERS OF NEGATIVE REFRACTIVITY SEPARATED BY AN AIR SPACE OF NEGATIVE CONFIGURATION, SAID LENS MEMBERS BEING OF SUBSTANTIALLY PLANOCONCAVE SHAPE WITH CONCAVE REAR SURFACES AND INCLUDING A SINGLET PRECEDED BY A DOUBLET WITH A FORWARDLY CONCAVE COLLECTIVE CEMENTED SURFACE, SAID SINGLET AND DOUBLET EACH HAVING A CONCAVE REAR SURFACE, THE REAR SURFACE OF SAID SINGLET BEING MORE STRONGLY CURVED THAN THAT OF SAID DOUBLET SAID PRINCIPAL OBJECTIVE CONSISTING OF FOUR AIRSPACED LENS MEMBERS INCLUDING A POSITIVE FIRST MEMBER, A NEGATIVE SECOND MEMBER, A POSITIVE THIRD MEMBER AND A POSITIVE FOURTH MEMBER, SAID FOURTH MEMBER BEING A BICONVEX LENS WITH FRONT AND REAR SURFACES RESPECTIVELY HAVING A SHORTER AND A LONGER RADIUS CURVATURE WITH AN ABSOLUTE RATIO LESS THAN 1:3. 